Process for preventing the corrosive action of sulphur-bearing petroleum hydrocarbons



J.. 2 i940. T, MCGEE 2,185,380

PRocEss Fon PREVENTING THE coRRosIvE ACTION oF suman-BEARING PETROLEUMHYnnocAnoNs Filed oct. 4. 1957 BY mvv/dbi AJ ATTORNEY.

Patented Jan. 2, 1940 STATES PATENT 4OFI-ECE Thomas L. McGee, Rosemead,Calif., assigner to .enkins Petroleum Process Company, Chicago, Ill., acorporation of Illinois Application October 4,

2 Claims.

My invention relates to a process for treating hydrocarbons, and moreparticularly to a process for treating sulphur-bearing petroleumhydrocarbons in the presence of finely divided metal or metallic alloy.

An object of my invention is to prevent the corrosive action of sulphuror sulphur compounds originally present or formed during the heattreatment of petroleum oils towards the metal of the apparatus in whichsuch oils are commonly treated; such corrosive action commonly occurringin the heating tubes, Vapor lines, separating columns, condensers andreceivers of the apparatus.

During cracking of oils containing suphur a portion of the latterconstituent or its compounds attacks the walls of the apparatus. Thesulphur compound thus produced7 admixing with carbon, forms anagglomerato closely adhering to the heating tube walls and reactionchamber, causing overheating of the former and generally foreshorteningthe run. An object of my invention is to inhibit the formation of suchagglomerate and thus prolong the operating cycle and life of theapparatus.

Distillates from sulphur bearing oils subjected to my process are alsomore readily refined to commercially acceptable standards for sulphurand corrosion: in many instances requiring no further treatment tocomply with such standards.

I am aware that inely divided metals have been used in the rening artchiey as catalysts in conjunction with the addition of hydrogen to theoil being processed, and that the use of various metallic oxides asdesulphurants is also a wellknown practice. My invention, however,differs from the prior art in providing for the continuous injection ofa finely divided desulphurizing metal or metals, either separately, orin physical mixture, or in alloy form into the oil being processedpreferably at the critical corrosive temperature of the latter and undercertain temperature differentials subsequently described. While any nelydivided metal or metallic alloy infusible and capable of acting on thesulphur or sulphur cornpound contained in the oil at the temperatureinvolved may be used, such as iron, copper, nickel, etc., I preferablyemploy iron on account of its cheapness and ready accessibility, and ina state of diminution from filings to a colloidal form; the latter statebeing the more effective. The quantity employed will vary with thenature of the sulphur or its compounds present and the temperaturesinvolved, i. e., with the critical corrosive temperature of the oilbeing processed or the tempera- 1937, Serial No. 167,088

ture at which the existent sulphur or its compounds begin their mostdeleterious action toward the metal of the apparatus. In some oils suchaction is most intense during simple distillation and in others extendsthrough the entire active cracking, separating and condensing stage. Theapproximate lower and upper corrosive temperature limits for most oilssubjected to my process appear to lie between 20C-1200o F. The metal (ormetals) employed, advantageously predispersed in a carrier oil ofrelatively low sulphur content such as recycle oil, is preferablyinjected into the main body of the oil undergoing treatment at apredetermined point or points in the heating system, although theinjection may be effected at other points and by other carriers assubsequently described. It appears preferable and the inventioncomprehends the introduction of the carrier oil with its dispersed metalat a substantial temperature differential from the main body of oilbeing processed, For example, in a cracking operation where it had beenpreviously established that the critical corrosive temperature of theoil processed was 720 F., i. e., that active sulphur corrosion began atsuch temperature, it was found most advantageous to inject the carrieroil with its dispersed metal (linely divided iron) at a temperature of750-850 the carrier oil being conveniently preheated before injectionthrough heat exchange or direct means. It has also been found that thecarrier oil may be introduced with fair results at a temperature belowthe main body being processed. Direct admixture of a portion of thefinely divided metal with the raw stock is frequently of advantage wheredisengagement of hydrogen sulphide occurs at a relatively lowtemperature. Preadmixture of the finely divided metal with the entirestock subjected to heat treatment while effective, requires a muchgreater quantity of metal to achieve the same result than where thelatter is introduced by a carrier stream. Where employed in such carrierstream the quantity of metal required is ordinarily substantiallyatomically equivalent to the sulphur present in the oil, whereas if themetallic element be preadmixed with the main body of oil to be treatedbefore the critical corrosive temperature is reached, a substantialexcess of metal over the atomic sulphur equivalent is required; ineither case the metal introduced being maintained in contact with thebody of oil during its entire heat treatment and any unchanged metaltogether with sulphur compounds thereof formed being drawn off with theresiduum and separated therefrom according to standard practice such asstagnation, filtration or the like if required.

In order that the invention may be more clearly understood, reference ismade to the accompanying drawing depicting in diagrammatic form one typeof apparatus suitable for carrying out the invention, wherein lrepresents a heating coil disposed in a conventional furnace Il, suchcoil being supplied with cycle oil through the line l2 by the pump I3taking suction through the line I4 from the dephlegmatingr column l5.Valve I6 controls the inlet pressure and valve ll the outlet pressure ofthe coil l5, the latter discharging through line i8 to the vessel I9from which residuum is withdrawn from the system through line 2U andcooling coil 2l as controlled by valve 22, While the vapors escapethrough line Z3 as controlled by valve 23a to the dephlegmating columnl5. Dephlegmated vapor from the latter passes through line 24 to acondenser (not shown) wherein vapor is condensed according to standardpractice and recovered. Raw stock is introduced to the system throughlines 25 and 25a, as controlled by valves 26 and 26a, by pump 2l takingsuction through line 28 from raw stock supply tank 29. Carrier oil, inwhich the metal employed is dispersed, is injected into coil l0 at apredetermined critical temperature, i. e., that at which sulphur orsulphur compounds become active, through the line by the pump 3l ascontrolled by valves 32, 32a, 33 and/or 33a; the pump 3l taking suctionthrough line 34 from the carrier oil tank 35, which is provided with amixing device (not shown) for incorporating the nely divided metal withthe carrier oil. A dierent, or the same metal may be introduced with theraw stock through line 3S, as controlled by valve 31, by pump 38 takingsuction through line 39 from tank 40, which like tank 35 is providedwith a mixing device (not shown). The carrier oil with its dispersedmetal may be heated by any desirable means (not shown) preferably to atemperature in excess of that of the oil processed at the point ofinjection.

The process is not limited to the method of injection or to the pointsof introduction of the nely divided metal, nor in general to theparticular apparatus shown which is to be understood in practice wouldbe equipped with various indicating and/or recording devices fortemperature, pressure and automatic controls commonly employed in theart. The invention is further not limited as to any pressure or to thetemperatures mentioned, which are given by way of example only, and whatI claim is new and desire to protect by Letters Patent is:

1. Process for preventing the corrosive action of sulphur-bearingpetroleum hydrocarbons towards the metal of the apparatus in which suchhydrocarbons are treated which comprises continuously injecting intosaid hydrocarbons upon attainment of an initial critical corrosivetemperature specific to said hydrocarbons finely divided iron dispersedin a carrier cil of relatively low sulphur content heated to atemperature approximately 150 F. in excess of said initial corrosivetemperature and maintaining such contact while said hydrocarbons existat a corrosive temperature.

2. Process for preventing the corrosive action of sulphur-bearingpetroleum hydrocarbons towards the metal of the apparatus in which suchhydrocarbons are treated f hich comprises continuously injecting intosaid hydrocarbons upon attainment of an initial critical corrosivetemperature of approximately 700 F. nnely divided iron dispersed in acarrier oil of relatively low sulphur content heated to a temperatureapproximately 150 F. in excess of said initial corrosive temperature andmaintaining such contact while said hydrocarbons exist at a crackingtemperature.

THOMAS L. MCGEE.

